Pneumatic artificial foot



May 25, 1948. E. L. STRICKLAND PNEUMATIC ARTIFICIAL FOOT Filed April 28,1945 INVENTOR. fawnv LSTR/CKLAND ATTORNEY- Patented May 25, 1948 TUNITED STATES PATENT oFFicE PNEUMATIC ARTIFICIAL FOOT Edwin L.Strickland, Richmond, Calif.

Application April 28, 1945, Serial No. 590,775

'2 Claims.

1 *I'his invention relates to improvements in an artificial "memberconstructed to serve as a walking "medium and has particular referenceto a pneumatic artificial foot wherein the ankle constru' ctioh is notonly provided with full lateral movement, but can be absolutely andpositively adjusted to fg-round level and will simulate in movement theaction of the human ankle.

The principal object of the invention is the provision of a "foot of thecharacter described that will relieve strain and fatigue in walking byutilizing an air cushion that eliminates jar to the body, and wherein byvirtue of the construction employed will result in a perfect adjustmentof the height to'the heel that relieves strain and effects a proper"balance.

A further object of the invention is the provision of a foot of thecharacter described that is strong, durable, neat in appearance, affordspositive protection to the working parts against the entrance of dirtand water in inclement weather, is readily "interchangeable, and yet ismost economical to manufacture.

Other objects and advantages will be apparent dnr ing the course of thefollowing description.

In the accompanying drawing wherein for the purpose of illustration isshown the preferred embodiment of the invention,

Fig. 1 is a view partly in section and partly in elevation illustratingthe appliance as secured to a wooden shin portion, illustrating theinflatable bag in the foot portion and the mechanism permitting movementof the foot portion relative to the ankle portion, and

Fig. 2 is a bottom plan view of the foot section showing the zipperarrangement whereby the parts may be readily removed for replacement 01'adjustment.

Referring to the drawing, the numeral 4 indicates the wooden portion ofan artificial leg member herein referred to as the shin portion providedwith a reduced recessed extremity 5 receivable in a top casting 6 thatis detachably secured by wood screws or other fastening elements 1 tosaid reduced extremity. It will be noted, as disclosed to advantage inFig. 1, that said casting is equipped with an enlarged bore 9 and acentral recess [0.

A cap casting or shell I l is fitted about the top casting 6, the sideof the cap casting being spaced from the undercut top wall or upper endI2 of the top casting 6 to permit the positioning therein of an annularwedge-shaped bead l3 provided in the upper end of a foot covering M, theconstruction and purpose of which will be later described. It

willibe noted that said shell 'or oasting H is of a greater thickness atthe front thereof as at 1-5 to thus provide :ameans or base for thereception of 'a machine screw 16 that serves to secure the shell H tothe cap casting 6. The said shell is provided with an opening ll incommunication and in alignment with the bore 9 to thus permit thepassingtherethrough of a heel and toe adjus'ting cable I8. 7

The numeral l9 indicates as awhole, 'an'instep casting so termed becauseit conform rs; the shape "of the instep. "This main body portion of thecasting is of substantial thickness and includes a tapered front portion20, a'curvedbottom portion 2|, and a substantially flat top wall 22. Thesaid casting has provided in its top "wall a mentral recess 23 and an'angu'lar'slot 25 and carries on its top wall a rubber bumper 25 that isreceivable in a slot 25 provided in the front thickened portion l5 ofthe shell 'rne "means for obtaining a lateral -ankle"rr'rovemen'tbetween the upper. casting construction I and the instep casting, tothus eliminatean'd' obtain the ankle movement of the humanfoot,comprisesa ball and socket joint thatcomprises a top insert bearing '21positioned in the recess It oi'the base 8 of the top casting and securedthereto by a machine screw 28; a lower insert bearing 29 that ispositioned in the central recess 23 of the main body portion of aninstep casting l9, and a bronze ball 30 free to rotate in the upper andlower bearings 21 and 29, and thus aiiording free lateral ankle movementand a positive adjustment of the ankle to ground levels.

To prevent the heel from flopping up and down I have provided thefollowing construction: A cable or wire I8 has brazed to its upper end athreaded extension 32. The lower end of the cable is connected to ananchor screw 33 that extends transverse of the body of the instepcasting. The said wire is encircled by a main spring that is positionedin the space 34 provided between the respective castings, the lower endof said spring being seated against a shoulder 35 provided by recessingthe upper surface of the instep casting. Since the upper end of thespring contacts the base of the top casting the spring will readilycontract and expand in the movement of the foot. To complete theassembly and to provide means for adjusting the heel portion a nut 36 isthreaded on the threaded extension 32 while an auxiliary spring 31encircles the upper end of the wire and is interposed between the baseof the nut and a shoulder 38 formed by recessing the top surface of thebase casting H adjacent th bore 9. V

a The foot portion l4, previously referred to, consists of a resilientmember that conforms to the 1 shape of a foot, which covering isadhesively secured to the instep casting as at A and B, and has itsupper wedge-shaped beaded extremity detachably secured between the uppercasting and the shell J I I Y It will be noted that an inflatable innertube 39 as illustrated to advantage inFig. 1 in a partly of said footmember relative to the shin portion to simulate the ankle movement ofthe human foot, a wedge shaped bead positioned on the 7 upper end ofsaid foot member for detachably deflated condition, is positioned withinsaid foot covering, and when inflated through the medium of a valve 39will completely fill the space C of the foot covering, thus presenting aresilient pneumatic foot base on which readily be placed. 7 r

A zipper element is indicated 40 and is provided in the base of the footcovering. It serves as a medium for withdrawing therethr-ou'gh themechanism above described when any of the parts of the constructionrequir repairing or necessitate adjustment.

If desired, ea liner maybe employed in the foot covering to prevent anyundue pinchingof the inflatable member. It is obvious that theemployment of the bumper; will absorb any undue shock in walking andthat the present construction presents an artificial pneumatic foot thataffords the maximum degree of ease and comfort and the absence offatigue'in walking. I

It is to be understood that the form of my invention herewith shown anddescribed is to be taken as a preferredvexample' of the same and thatvariouschanges relative to the shape size,

material and arrangement of parts may be readily resorted to withoutdeparting'from'the spirit of the invention or the scope of the subjoinedclaims.

' Havingthusdescribed my invention, I claim:

7 1. An artificial foot comprising a top casting secured to the shinportion of an artificial leg, anein'step casting; a pneumatic tuberetaining 7 foot member secured to said instep casting,

means interposed between said casting and se-' cured'thereto andpermitting lateral movement by the numeral a standard shoe can securingthe latter to said top castingrand a closure means in the form of azipper provided in the base of said foot member, whereby access isobtained to the interior of said foot member and said castings.

'2. An artificial.- foot comprising atop casting secured to the shinportionof an artificial leg,

the lower surface of said casting being recessed,

- an instep casting, a pneumatic tube retaining foot member secured tosaid instep casting; means interposed between said castings and securedthereto and permitting lateral movement of said foot member relative tothe shin'p-o-rtion to simulate the ankle'movementof the human foot, saidmeans comprising a ball and socket joint, a buffer mounted on the uppersurface of the front portion of said instep casting andrreceivable inthe recess on the lower surface ofjsaid top caste ing, and adjustinmeans positioned between said castings to adjust height to the heel,said adjusting means comprising a wire connecting said castings andbeing; interposed between the rear portions of said castings, and a mainspringIand an auxiliaryspring encirclin said Wire, the main; springbeing .positionegi pbetween'rthe upper and lower castings, the auxiliaryspring being housed Number" jNam e p v 708,685 White v Sept, 9, 1902827,720 Erwin Aug; 7, 1.906 r 1,151,144 Wolfe et al. ,Aug. '24, 19151,804,915' co11ins; May 12,, 1931 a in the recess of the shin portion ofthe artificial leg. 7 7

The following references are of record in the

